Growth factor receptors signaling in glioblastoma cells: therapeutic implications

Intracellular Pathways and Mechanisms of Colored Secondary Metabolites in Cancer Therapy

Despite the great advancements made in cancer treatment, there are still many unsatisfied aspects, such as the wide palette of side effects and the drug resistance. There is an obvious increasing scientific attention towards nature and what it can offer the human race. Natural products can be used to treat many diseases, of which some plant products are currently used to treat cancer. Plants produce secondary metabolites for their signaling mechanisms and natural defense. A variety of plant-derived products have shown promising anticancer properties in vitro and in vivo. Rather than recreating the natural production environment, ongoing studies are currently setting various strategies to significantly manipulate the quantity of anticancer molecules in plants. This review focuses on the recently studied secondary metabolite agents that have shown promising anticancer activity, outlining their potential mechanisms of action and pathways.

Oncogenic Signalling of Growth Factor Receptors in Cancer: Mechanisms and Therapeutic Opportunities

Cancer is a common name for several distinct diseases caused by uncontrolled cell growth and proliferation [...]

Glioblastoma Stem Cells-Useful Tools in the Battle against Cancer

Glioblastoma stem cells (GSCs) are cells with a self-renewal ability and capacity to initiate tumors upon serial transplantation that have been linked to tumor cell heterogeneity. Most standard treatments fail to completely eradicate GSCs, causing the recurrence of the disease. GSCs could represent one reason for the low efficacy of cancer therapy and for the short relapse time. Nonetheless, experimental data suggest that the presence of therapy-resistant GSCs could explain tumor recurrence. Therefore, to effectively target GSCs, a comprehensive understanding of their biology and the survival and developing mechanisms during treatment is mandatory. This review provides an overview of the molecular features, microenvironment, detection, and targeting strategies of GSCs, an essential information required for an efficient therapy. Despite the outstanding results in oncology, researchers are still developing novel strategies, of which one could be targeting the GSCs present in the hypoxic regions and invasive edge of the glioblastoma.

Target Specific Inhibition of Protein Tyrosine Kinase in Conjunction With Cancer and SARS-COV-2 by Olive Nutraceuticals

The fact that viruses cause human cancer dates back to the early 1980s. By reprogramming cellular signaling pathways, viruses encoded protein that can regulate altered control of cell cycle events. Viruses can interact with a superfamily of membrane bound protein, receptor tyrosine kinase to modulate their activity in order to increase virus entrance into cells and promotion of viral replication within the host. Therefore, our study aimed at screening of inhibitors of tyrosine kinase using natural compounds from olive. Protein tyrosine kinase (PTK) is an important factor for cancer progression and can be linked to coronavirus. It is evident that over expression of Protein tyrosine kinase (PTK) enhance viral endocytosis and proliferation and the use of tyrosine kinase inhibitors reduced the period of infection period. Functional network studies were carried out using two major PTKs viz. Anaplastic lymphoma kinase (ALK) and B-lymphocytic kinase (BTK). They are associated with coronavirus in regulation of cell signaling proteins for cellular processes. We virtually screened for 161 library of natural compounds from olive found overexpressed in ALK and BTK in metastatic as well as virus host cells. We have employed both ligand and target-based approach for drug designing by high throughput screening using Multilinear regression model based QSAR and docking. The QSAR based virtual screening of 161 olive nutraceutical compounds has successfully identified certain new hit; Wedelosin, in which, the descriptor rsa (ratio of molecular surface area to the solvent accessible surface area) plays crucial role in deciding Wedelosin’s inhibitory potency. The best-docked olive nutraceuticals further investigated for the stability and effectivity of the BTK and ALK during in 150 ns molecular dynamics and simulation. Post simulation analysis and binding energy estimation in MMGBSA further revealed the intensive potential of the olive nutraceuticals in PTK inhibition. This study is therefore expected to widen the use of nutraceuticals from olive in cancer as well as SARS-CoV2 alternative therapy.

Glioblastoma pharmacotherapy: A multifaceted perspective of conventional and emerging treatments (Review)

Due to its localisation, rapid onset, high relapse rate and resistance to most currently available treatment methods, glioblastoma multiforme (GBM) is considered to be the deadliest type of all gliomas. Although surgical resection, chemotherapy and radiotherapy are among the therapeutic strategies used for the treatment of GBM, the survival rates achieved are not satisfactory, and there is an urgent need for novel effective therapeutic options. In addition to single-target therapy, multi-target therapies are currently under development. Furthermore, drugs are being optimised to improve their ability to cross the blood-brain barrier. In the present review, the main strategies applied for GBM treatment in terms of the most recent therapeutic agents and approaches that are currently under pre-clinical and clinical testing were discussed. In addition, the most recently reported experimental data following the testing of novel therapies, including stem cell therapy, immunotherapy, gene therapy, genomic correction and precision medicine, were reviewed, and their advantages and drawbacks were also summarised.

ELTD1-An Emerging Silent Actor in Cancer Drama Play

The epidermal growth factor, latrophilin, and seven transmembrane domain–containing protein 1 (ELTD1), is a member of the G–protein coupled receptors (GPCRs) superfamily. Although discovered in 2001, ELTD1 has been investigated only by a few research groups, and important data about its role in normal and tumor cells is still missing. Even though its functions and structure are not yet fully understood, recent studies show that ELTD1 has a role in both physiological and pathological angiogenesis, and it appears to be a very important biomarker and a molecular target in cancer diseases. Upregulation of ELTD1 in malignant cells has been reported, and correlated with poor cancer prognosis. This review article aims to compile the existing data and to discuss the current knowledge on ELTD1 structure and signaling, and its role in physiological and neoplastic conditions.

The Interference between SARS-CoV-2 and Tyrosine Kinase Receptor Signaling in Cancer

Cancer and viruses have a long history that has evolved over many decades. Much information about the interplay between viruses and cell proliferation and metabolism has come from the history of clinical cases of patients infected with virus-induced cancer. In addition, information from viruses used to treat some types of cancer is valuable. Now, since the global coronavirus pandemic erupted almost a year ago, the scientific community has invested countless time and resources to slow down the infection rate and diminish the number of casualties produced by this highly infectious pathogen. A large percentage of cancer cases diagnosed are strongly related to dysregulations of the tyrosine kinase receptor (TKR) family and its downstream signaling pathways. As such, many therapeutic agents have been developed to strategically target these structures in order to hinder certain mechanisms pertaining to the phenotypic characteristics of cancer cells such as division, invasion or metastatic potential. Interestingly, several authors have pointed out that a correlation between coronaviruses such as the SARS-CoV-1 and -2 or MERS viruses and dysregulations of signaling pathways activated by TKRs can be established. This information may help to accelerate the repurposing of clinically developed anti-TKR cancer drugs in COVID-19 management. Because the need for treatment is critical, drug repurposing may be an advantageous choice in the search for new and efficient therapeutic compounds. This approach would be advantageous from a financial point of view as well, given that the resources used for research and development would no longer be required and can be potentially redirected towards other key projects. This review aims to provide an overview of how SARS-CoV-2 interacts with different TKRs and their respective downstream signaling pathway and how several therapeutic agents targeted against these receptors can interfere with the viral infection. Additionally, this review aims to identify if SARS-CoV-2 can be repurposed to be a potential viral vector against different cancer types.

Updated Insights on EGFR Signaling Pathways in Glioma

Nowadays, due to recent advances in molecular biology, the pathogenesis of glioblastoma is better understood. For the newly diagnosed, the current standard of care is represented by resection followed by radiotherapy and temozolomide administration, but because median overall survival remains poor, new diagnosis and treatment strategies are needed. Due to the quick progression, even with aggressive multimodal treatment, glioblastoma remains almost incurable. It is known that epidermal growth factor receptor (EGFR) amplification is a characteristic of the classical subtype of glioma. However, targeted therapies against this type of receptor have not yet shown a clear clinical benefit. Many factors contribute to resistance, such as ineffective blood-brain barrier penetration, heterogeneity, mutations, as well as compensatory signaling pathways. A better understanding of the EGFR signaling network, and its interrelations with other pathways, are essential to clarify the mechanisms of resistance and create better therapeutic agents.

The effect of temozolomide in combination with doxorubicin in glioblastoma cells in vitro

BACKGROUND

Prior to 2000, the DNA alkylating agents nitrosoureas were used as standard treatment of glioblastoma. Current treatments for glioblastoma patients consist of surgery followed by radiation in combination with temozolomide. Despite therapeutic advances, the prognosis for glioblastoma patients remains grim, with a five-year overall survival below 15%. In this study, our team analyzed the interaction between temozolomide and doxorubicin in a glioblastoma cell line, in vitro.

MATERIALS AND METHOD

The cell line, established from a patient who underwent surgery at the "Bagdasar Arseni Emergency Hospital", was exposed to 10 µM and 100 µM of temozolomide and 10 nM and 100 nM of doxorubicin, respectively, over a period of 7, 10 and 14 days, in monotherapy and in combination.

RESULTS

The results showed that both temozolomide (66.5% cytotoxicity for the 10 µM dose at 14 days) de and doxorubicin (66.8% cytotoxicity for the 10 nM dose after 14 days) were very effective in killing cancer cells in monotherapy, but failed to produce a synergistic effect when used in combination.

CONCLUSION

While the results may be discouraging, they present an interesting prospect into how certain drug interactions can impact treatment response.

Receptor tyrosine kinase targeting in glioblastoma: performance, limitations and future approaches

From all central nervous system tumors, gliomas are the most common. Nowadays, researchers are looking for more efficient treatments for these tumors, as well as ways for early diagnosis. Receptor tyrosine kinases (RTKs) are major targets for oncology and the development of small-molecule RTK inhibitors has been proven successful in cancer treatment. Mutations or aberrant activation of the RTKs and their intracellular signaling pathways are linked to several malignant diseases, including glioblastoma. The progress in the understanding of malignant glioma evolution has led to RTK targeted therapies with high capacity to improve the therapeutic response while reducing toxicity. In this review, we present the most important RTKs (i.e. EGFR, IGFR, PDGFR and VEGFR) currently used for developing cancer therapeutics together with the potential of RTK-related drugs in glioblastoma treatment. Also, we focus on some therapeutic agents that are currently at different stages of research or even in clinical phases and proved to be suitable as re-purposing candidates for glioblastoma treatment.

Benefits of Nanomedicine for Therapeutic Intervention in Malignant Diseases

Cancer remains one of the most difficult to manage healthcare problems. The last two decades have been considered the golden age of cancer research, with major breakthroughs being announced on a regular basis. However, the major problem regarding cancer treatment is the incapability to selectively target cancer cells, with certain populations of tumors still remaining alive after treatment. The main focus of researchers is to develop treatments that are both effective and selective in targeting malignant cells. In this regard, bioavailability can be increased by overcoming the biological barriers encountered in the active agent’s pathway, creating carrier vehicles that have the ability to target malignant cells and effectively release the active agent. Since its appearance, nanomedicine has provided many answers to these challenges, but still, some expectations were not satisfied. In this review, we focused on the most recent developments in targeted drug delivery. Furthermore, a summary of different types of nanoparticles used to deliver active therapeutic agents in oncology is presented, along with details on the nanodrugs that were clinically approved by the Food and Drug Administration (FDA), until April 2019.

Platelet-Derived Growth Factor Receptor and Ionizing Radiation in High Grade Glioma Cell Lines

Treatment of high grade gliomas (HGGs) has remained elusive due to their high heterogeneity and aggressiveness. Surgery followed by radiotherapy represents the mainstay of treatment for HGG. However, the unfavorable location of the tumor that usually limits total resection and the resistance to radiation therapy are the major therapeutic problems. Chemotherapy with DNA alkylating agent temozolomide is also used to treat HGG, despite modest effects on survival. Disregulation of several growth factor receptors (GFRs) were detected in HGG and receptor amplification in glioblastoma has been suggested to be responsible for heterogeneity propagation through clonal evolution. Molecularly targeted agents inhibiting these membrane proteins have demonstrated significant cytotoxicity in several types of cancer cells when tested in preclinical models. Platelet-derived growth factor receptors (PDGFRs) and associated signaling were found to be implicated in gliomagenesis, moreover, HGG commonly display a Platelet-derived growth factor (PDGF) autocrine pathway that is not present in normal brain tissues. We have previously shown that both the susceptibility towards PDGFR and the impact of the PDGFR inactivation on the radiation response were different in different HGG cell lines. Therefore, we decided to extend our investigation, using two other HGG cell lines that express PDGFR at the cell surface. Here, we investigated the effect of PDGFR inhibition alone or in combination with gamma radiation in 11 and 15 HGG cell lines. Our results showed that while targeting the PDGFR represents a good means of treatment in HGG, the combination of receptor inhibition with gamma radiation did not result in any discernable difference compared to the single treatment. The PI3K/PTEN/Akt/mTOR and Ras/Raf/MEK/ERK pathways are the major signaling pathways emerging from the GFRs, including PDGFR. Decreased sensitivity to radiation-induced cell death are often associated with redundancy in these pro-survival signaling pathways. Here we found that Phosphoinositide 3-kinases (PI3K), Extracellular-signal-regulated kinase 1/2 (ERK1/2), or c-Jun N-terminal kinase 1/2 (JNK1/2) inactivation induced radiosensitivity in HGG cells.

The Influence of EGFR Inactivation on the Radiation Response in High Grade Glioma

Lack of effectiveness of radiation therapy may arise from different factors such as radiation induced receptor tyrosine kinase activation and cell repopulation; cell capability to repair radiation induced DNA damage; high grade glioma (HGG) tumous heterogeneity, etc. In this study, we analyzed the potential of targeting epidermal growth factor receptor (EGFR) in inducing radiosensitivity in two human HGG cell lines (11 and 15) that displayed similar growth patterns and expressed the receptor protein at the cell surface. We found that 15 HGG cells that express more EGFR at the cell surface were more sensitive to AG556 (an EGFR inhibitor), compared to 11 HGG cells. Although in line 15 the effect of the inhibitor was greater than in line 11, it should be noted that the efficacy of this small-molecule EGFR inhibitor as monotherapy in both cell lines has been modest, at best. Our data showed a slight difference in the response to radiation of the HGG cell lines, three days after the treatment, with line 15 responding better than line 11. However, both cell lines responded to ionizing radiation in the same way, seven days after irradiation. EGFR inhibition induced radiosensitivity in 11 HGG cells, while, in 15 HGG cells, the effect of AG556 treatment on radiation response was almost nonexistent.

Cancer stem cells: biological functions and therapeutically targeting

Almost all tumors are composed of a heterogeneous cell population, making them difficult to treat. A small cancer stem cell population with a low proliferation rate and a high tumorigenic potential is thought to be responsible for cancer development, metastasis and resistance to therapy. Stem cells were reported to be involved in both normal development and carcinogenesis, some molecular mechanisms being common in both processes. No less controversial, stem cells are considered to be important in treatment of malignant diseases both as targets and drug carriers. The efforts to understand the role of different signalling in cancer stem cells requires in depth knowledge about the mechanisms that control their self-renewal, differentiation and malignant potential. The aim of this paper is to discuss insights into cancer stem cells historical background and to provide a brief review of the new therapeutic strategies for targeting cancer stem cells.

MicroRNA-503 acts as a tumor suppressor in glioblastoma for multiple antitumor effects by targeting IGF-1R

microRNA (miRNA) dysregulation is associated with various types of human cancer by regulating cancer cell survival, proliferation and invasion. Aberrant expression of microRNA-503 (miR-503) has been reported in several cancer profiles. However, potential linkage of miR-503 levels and the underlying regulatory mechanisms in human glioblastoma multiforme (GBM) remain unclear. In the present study, we showed for the first time that the expression of miR-503 was significantly reduced in GBM tissues and cell lines (U251 and U87MG) relative to normal brain tissues. Furthermore, our results demonstrated that overexpression of miR-503 in GBM cell lines not only suppressed cell proliferation through inducing G0/G1 cell cycle arrest and apoptosis, but also inhibited cancer cell migration and tumor invasion. In addition, we identified insulin-like growth factor-1 (IGF-1R) receptor mRNA is a bona fide target of miR-503 by computational analysis followed by luciferase reporter assays. Of note, upregulation of miR-503 in GBM cells suppressed endogenous IGF-1R protein expression. Further mechanistic analysis revealed that forced expression of miR-503 inhibited AKT activation, suggesting the tumor suppressive effect of miR-503 in GBM cells is partially mediated by phosphatidylinositol 3-kinase/AKT signaling. Taken together, the results of the present study demonstrated that miR-503 is a tumor suppressor for GBM and a favorable factor against glioma progression through targeting IGF-1R, thus providing a new evidence-supported prognostic marker for GBM diagnosis.

Bayesian methods for expression-based integration of various types of genomics data

: We propose methods to integrate data across several genomic platforms using a hierarchical Bayesian analysis framework that incorporates the biological relationships among the platforms to identify genes whose expression is related to clinical outcomes in cancer. This integrated approach combines information across all platforms, leading to increased statistical power in finding these predictive genes, and further provides mechanistic information about the manner in which the gene affects the outcome. We demonstrate the advantages of the shrinkage estimation used by this approach through a simulation, and finally, we apply our method to a Glioblastoma Multiforme dataset and identify several genes potentially associated with the patients' survival. We find 12 positive prognostic markers associated with nine genes and 13 negative prognostic markers associated with nine genes.

Glioblastoma: synergy of growth promotion between CCL5 and NK-1R can be thwarted by blocking CCL5 with miraviroc, an FDA approved anti-HIV drug and blocking NK-1R with aprepitant, an FDA approved anti-nausea drug

WHAT IS KNOWN AND BACKGROUND

Two receptor signaling pathways that are commonly active in facilitating glioblastoma growth and invasion- that of CCR5 and neurokinin (NK)-1R- have small molecule inhibitors that are FDA approved and marketed to treat other conditions. The anti-HIV drug, maraviroc, inhibits human CCR5's ligand from binding, and hence blocks CCR5 stimulation. The anti-nausea drug aprepitant blocks substance P signaling at NK-1R.

AIMS AND OBJECTIVE

We propose on the basis of molecular insights that a combination of the two drugs is likely to be useful in the treatment of glioblastoma.

COMMENT

After stimulation by their respective ligands both CCR5 and NK-1R, through intermediaries, phosphorylate and thereby activate ERK1/2, triggering in turn migratory and mitotic events. Neurokinin-1R second messenger signaling also happens to serine phosphorylate CCR5. Phosphorylated CCR5 exhibits amplified activity after agonist ligation. Therefore, aprepitant and maraviroc combined treatment is expected to exert synergestic inhibition of growth enhancing signaling in glioblastoma. Inhibiting an amplifier is equivalent to amplifying an inhibitor. Since the two suggested drugs are non-cytotoxic they are envisioned as adjunctive treatments to current standard temozolomide, radiation, and bevacizumab, all to be used after debulking primary resection.

WHAT IS NEW AND CONCLUSION

Our analysis makes the case for a well-designed trial of the proposed combination in the treatment of glioblastoma.

NFκB inhibitors induce cell death in glioblastomas

Identification of novel target pathways in glioblastoma (GBM) remains critical due to poor prognosis, inefficient therapies and recurrence associated with these tumors. In this work, we evaluated the role of nuclear-factor-kappa-B (NFκB) in the growth of GBM cells, and the potential of NFκB inhibitors as antiglioma agents. NFκB pathway was found overstimulated in GBM cell lines and in tumor specimens compared to normal astrocytes and healthy brain tissues, respectively. Treatment of a panel of established GBM cell lines (U138MG, U87, U373 and C6) with pharmacological NFκB inhibitors (BAY117082, parthenolide, MG132, curcumin and arsenic trioxide) and NFκB-p65 siRNA markedly decreased the viability of GBMs as compared to inhibitors of other signaling pathways such as MAPKs (ERK, JNK and p38), PKC, EGFR and PI3K/Akt. In addition, NFκB inhibitors presented a low toxicity to normal astrocytes, indicating selectivity to cancerous cells. In GBMs, mitochondrial dysfunction (membrane depolarization, bcl-xL downregulation and cytochrome c release) and arrest in the G2/M phase were observed at the early steps of NFκB inhibitors treatment. These events preceded sub-G1 detection, apoptotic body formation and caspase-3 activation. Also, NFκB was found overstimulated in cisplatin-resistant C6 cells, and treatment of GBMs with NFκB inhibitors overcame cisplatin resistance besides potentiating the effects of the chemotherapeutics, cisplatin and doxorubicin. These findings support NFκB as a potential target to cell death induction in GBMs, and that the NFκB inhibitors may be considered for in vivo testing on animal models and possibly on GBM therapy.

Temozolomide in malignant glioma

Glioblastoma multiforme WHO grade IV (GBM) is the most aggressive malignant glioma and the most frequent primary tumor of the central nervous system. The median survival of newly diagnosed GBM patients was between 9 to 12 months prior to treatment with temozolomide being introduced. Primary resection that is as complete as possible is recommended for malignant glioma. Conventional fractionated irradiation 55 to 60 gy with concomitant temozolomide followed by standard temozolomide 6 cycles (5/28) (EORTC/NCIC-regime published by R Stupp in 2005) is the standard of care for newly diagnosed GBM after surgery, independent of the methylation status of the MGM-T gene promoter. Age is no contraindication for treatment with temozolomide, although comorbidity and performance status have to be considered. For temozolomide naive GBM and astrocytoma grade III patients with disease progression, temozolomide is still the treatment of choice outside of clinical studies. A general consensus regarding the schedule of choice has not yet been achieved; so far the 5 out of 28 days regimen (5/28) is the standard of care in most countries. Patients with disease progression after standard temozolomide (5/28) are candidates for clinical studies. Outside of clinical studies, dose-dense (7/7), prolonged (21/28), or metronomic (28/28) temozolomide, or alternatively a nitrosourea-based regimen can be an option. The excellent toxicity profile of temozolomide allows for various combinations with antitumor agents. None of these combinations, however, have been demonstrated to be statistically significantly superior compared to temozolomide alone. The role of lower dosed, dose-dense, or continuous regimen with or without drug combination and the role of temozolomide for newly diagnosed astrocytoma grade III and low grade glioma still has to be determined.

Helianthin induces antiproliferative effect on human glioblastoma cells in vitro

A major focus of brain cancer research today is to translate understanding of glioma biology into advances in treatment, by exploring the potential of target therapy. Here we investigated the ability of three compounds belonging to the chemical class of azo dyes (methyl red, methyl yellow, and helianthin) to inhibit glioblastoma (GB) cell growth in vitro. Our results showed that helianthin induced cytotoxicity in two GB cell cultures, cell lines 18 and 38, whereas methyl red and methyl yellow were not cytotoxic. The effect of helianthin on EGFR, IGF-1R, and their common intracellular signaling via PI3-K and ERK1/2 was also analyzed. Treatment with helianthin down-regulated EGFR and IGF-1R activity in both cell lines. Helianthin treatment blocked ERK1/2 phosphorylation without affecting PI3K activity in cell line 18 and reduced both PI3K and ERK1/2 in GB 38 cell line. The cell death was accompanied by degradation of PARP without affecting BCL2 expression in both GB cell cultures. Because of the genetic heterogeneity of malignant gliomas, we tested the effect of helianthin on other two primary GB lines (11 and 15) and two early-passage GB cultures (BT1GB and BT2GB), to assess the general nature of the anti-tumor effect of the drug in GB cells. We found that helianthin treatment induced cell death in all the GB cell cultures analyzed. To our knowledge, this is the first report indicating that helianthin can reduce GB cell growth.